Currently, a large number of devices conduct communications mutually using an IPv6 (Internet protocol version 6). In order to provide mobile equipment with mobility support, IETF (Internet Engineering Task Force) is developing techniques based on MIPv6 (Mobility Support in IPv6) (see the following Non-Patent Document 1).
The mobility support described in Non-Patent Document 1 is put into practice by introducing an entity known as a home agent (HA) to a home network. A mobile node (MN) uses a binding update (BU) message to register a care-of address (CoA) with the home agent. This binding update allows the home agent to generate binding between the home address (HoA) (address acquired at a home link) and the care-of address of the mobile node. The home agent has a function of receiving (intercepting) a message addressed to the home address of the mobile node and using encapsulation of a packet (this means that a certain packet is made a payload of a new packet, which is known as a packet tunneling also) to transfer the packet to the care-of address of the mobile node.
MIPv6 further specifies a method of route optimization (RO) in communication with a correspondent node (CN). This RO mechanism allows a MN to register its own care-of address with a CN, whereby the MN and the CN can conduct a mutual communication using the care-of address of the MN while bypassing the home agent of the MN. Further, the CN can understand the effectiveness of the care-of address of the MN using a return routability (RR) test. The return routability is started from the MN, showing to the CN that the care-of address of the MN is in association with the home address of the MN (that is, the care-of address and the home address are used by a common MN). Note here that this RO mechanism is optional, which is effective only when the CN supports a function of the RO mechanism.
One of the problems of MIPv6 resides in that a HA and a CN (both may be plural) have to updated every time a connection point of a MN with a network is changed. Because of this problem, when a MN travels fast, for example, a lot of signaling associated with a change in location information of the MN generates in a short time, causing an increase in throughput given to the network.
Further, a RR test and the transmission of a BU message are conducted when a connection point with a network is changed, and therefore a handoff time occurs with the CN every time a connection point with a network is changed. Since it takes a considerable time to complete the handoff, jitter and packet loss are generated in a flow in a communication with a CN and a session associated therewith. Such jitter is inconvenient for VoIP (Voice over IP), multimedia streaming and video streaming, and such packet loss is inconvenient for a flow to transmit important text data information. Herein, even when TCP (Transmission Control Protocol) is used for an application dealing with important text data information, a packet is resent due to packet loss, thus degrading throughput of the TOP.
In order to solve such problems of MIPv6, a large number of types of terminal-based local mobility management protocols have been proposed. One of the most known protocols among them is HMIPv6 (Hierarchical Mobility Management Protocol version 6). Currently, this HMIPv6 has become IETF standard.
For instance, an object of the terminal-based local mobility management protocol including HMIPv6 is to decrease signaling load (an increase in band consumption and signaling throughput due to signaling) generated by movement of a MN and to decrease handoff delay. In such terminal-based local mobility management protocol, however, a MN needs to transmit BU to a MAP (Mobility Anchor Point) even when a connection point is changed in a local mobility management domain. Thus, every time a connection point is changed, the MN needs to transmit some signaling through a wireless access network, thus leading to a problem of extra battery power of the MN consumed to transmit signaling for location information updating in such a local domain.
Meanwhile, a network-based local mobility management (NETLMM) working group in IETF is discussing about protocol achieving the same object as of the terminal-based local mobility management protocol (for example, see the following Non-Patent Document 2). The network-based local mobility management protocol uses network-based local mobility management signaling instead of terminal-based local mobility management signaling.
One type of such network-based local mobility management protocol discussed in the NETLMM working group includes proxy mobile IPv6 (PMIPv6). This protocol is the most supported in the NETLMM working group, having a possibility of being adopted as a standard protocol for network-based local mobility management services.
PMIPv6 is a technique attempted to achieve MIPv6-based mobility management in a local domain using a function of a proxy mobility agent (PMA) provided in MAG (Mobile Access Gateway). PMIPv6 is mainly configured to support mobility in a local place of a network for an IPv6 host that does not implement CMIPv6 (Client Mobile IPv6) stack. Note here that CMIP makes a terminal itself conduct mobile IP processing, which is an opposite idea of PMIP that makes any proxy node existing on the network side conduct mobile IP processing of a terminal as proxy.
In PMIPv6, location management signaling in a local domain is completely processed by a network, and therefore PMIPv6 is effective for a node implementing CMIPv6 stack as well. During global movement involving a change of a MN address, the MN has to use CMIP stack to transmit related location update signaling (e.g., BU signaling of MIPv6) to a HA and a CN. On the other hand, in the case of movement in a PMIPv6 local domain, MN understands that a prefix is not changed and the same prefix is kept, so that the MN does not conduct location registration signaling.
A prefix used by a MN in a PMIPv6 domain is acquired from a network managed by local mobility anchor (LMA), that is, the LMA serves as a logical anchor point of this prefix. In a local PMIPv6 domain, a MAG conducts location registration signaling to the LMA instead of the MN so as to associate a MN address (PMIPv6 domain address) in the PMIPv6 domain or a prefix provided to the MN with an address of an egress interface of the MAG itself. When detecting a connection of a MN, the MAG basically conducts, with respect to the LMA, appropriate proxy signaling similar to BU in MIPv6.
In the case where the home agent of the MN and the LMA are implemented by the same device, this PMIPv6 domain is the home domain of the MN, and the MN does not need to conduct signaling, so that the MN can receive original PMIPv6 services. On the other hand, in the case where the MN exists in a foreign PMIPv6 domain and a foreign prefix is provided to the MN, the MN has to provide a newly acquired address in the foreign PMIPv6 domain to the HA and the CN for updating. Herein, the operating range of this protocol is within a specific management domain, and such an operating range might expand over a large scale of range. For instance, a global PMIPv6 domain of a scale across the world can be formed by cooperation of a large number of operators.
When moving in a PMIPv6 domain, a MN acquires a local prefix. Normally, after being subjected to authorization by an AAA (Authorization, Authentication and Accounting) server, the MN is provided with a local prefix. The local prefix provided to the MN may be a prefix specific to each MN or may be a common prefix that is the same as the prefix of the LMA address. When a prefix specific to each MN is provided, an address is configured in a stateful or stateless address configuration mode. On the other hand, when a common prefix is provided to a MN, a stateful address configuration is more desirable so as to avoid a problem of overlapping addresses generated by the MN in the PMIPv6 domain.
A major drawback of PMIPv6 resides in that since a service thereof is provided in a local place of a global network, a MN attempting global movement (moving across PMIPv6 domains) has to use PMIPv6 and MIPv6 at the same time as described in the following Patent Document 3. Further, since a PMIPv6 service is limited to a local domain, global mobility cannot be achieved in a real sense for an IPv6 host unless different PMIPv6 domains cooperate with each other.
PMIPv6 further has a problem about route optimization of a moving IPv6 host. A CMIP node (i.e., a MN executing an operation based on MIP) can always execute RO with a CN at the time of address change. On the other hand, in order to allow an IPv6 host not having a RO function to conduct RO, support from another entity existing on a network is required. The following Non-Patent Document 4 discloses a method of achieving RO for an IPv6 host in a PMIPv6 domain. In the Non-Patent Document 4, a PMA conducts RO between an IPv6 host and a CN thereof.
Further, 3GPP (Third Generation Partnership Project) is discussing about a global heterogeneous network communication device having a communication function with various wireless access networks such as a wireless local area network (WLAN), a cellular network (3G) and a WiMAX type wireless wide area network (WWAN). Especially, they are discussing to realize seamless mobility in a heterogeneous network communication device and support for a plurality of application services requiring real-time video, VoIP, and a high QoS (Quality of Service) for important data.
As disclosed in the following Non-Patent Document 5, in order to allow user equipment (UE) to efficiently move in various local management domains (including various types of access networks and core networks), it is important for 3GPP to adapt to an appropriate mobility management mechanism.
In 3GPP, access networks can be categorized into: legacy 3GPP access networks (GPRS: General Packet Radio System/UMTS: Universal Mobile Telecommunications System); evolved 3GPP access networks; trusted non-3GPP access networks (trusted WiMAX access networks); and I-WLANs (interworking WLAN: enabling non-trusted access from WLAN via trusted gateway called e-PDG (evolved Packet Data Gateway)).
Non-Patent Document 5 describes that in 3GPP, PMIPv6 is the most appropriately used for a plurality of different types of network-based local mobility management. This is because, in addition to the above-described advantage specific to PMIPv6, even 3GPP legacy UE not implementing a MIPv6 function can realize network based local mobility management in a local place of a 3GPP network.
The following Patent Document 1 discloses a method of notifying a MN of two prefixes. Herein one of the prefixes notified to the MN is a local prefix, which is a prefix notified from an AR or a prefix related to an AR address. The other prefix is an address of a MA (Mobility Agent). Herein, a local network segment where the MN receives the MA address is called a local mobility domain.
The MN configures two care-of addresses based on the notified two prefixes. The addresses configured by the MN from the prefix related to the AR and the MA prefix (the prefix related to the MA address) are called a local address and a global address, respectively. Every time a sub-network is changed in a local domain, the MN generates a local care-of address, associates the local address with the global address of the MN and notifies the MA of the same. A HA or a CN is notified only when a mobility agent changes. Binding notified to the HA or the CN is binding between the home address of the MN and the global address of the MN.
The MONAMI6 (Mobile Nodes and Multiple Interfaces in IPv6) of IETF as disclosed in the following Non-Patent Document 6 provides a function of allowing a mobile node with a plurality of interfaces (multi-interface) to make full use of an advantage of multimode. The multi-interface node can register a plurality of care-of addresses acquired at its interfaces with a home agent. Thereby, the home agent can understand that a mobile node can be reached via a plurality of routes. Although according to the earlier MIPv6 standard, a home agent can register only one primary care-of address therein, this Non-Patent Document 6 discloses an additional option called a binding identifier (BID) provided to signaling to register a plurality of care-of addresses (MCoA: Multiple CoA), thus associating the plurality of care-of addresses with one home address. Herein, to register a plurality of care-of addresses for one home address is called MCoA registration.
The following Patent Document 2 discloses a method of realizing route optimization and location privacy (location concealment) in a hierarchical (local mobility and global mobility) mobility management environment. When a MN moves in a local mobility management segment under the control of a local mobility anchor, the MN registers a local care-of address thereof to a LMA or an AR operates as a proxy of the MN by a proxy method to register the local care-of address of the MN with the LMA. In the case of such local registration, the LMA is notified of a HA address of the MN. The LMA conducts binding update to notify a home agent of the MN of the LMA address as the care-of address of the MN. Thereby, a packet transmitted from the CN is received (intercepted) by the HA, and is tunneled to the LMA. When a proxy registration mode is valid, the LMA tunnels a packet to the MN or the AR.
Patent Document 2 further deals with a problem of route optimization. Herein, a gateway on the CN side (a gateway connecting with the CN) can make an inquiry about a current care-of address of a MN to a HA. In response to this inquiry, the HA makes a notification of the LMA address as the current care-of address of the MN. When the HA provides the LMA address, a tunnel is formed between the gateway node on the CN side and the LMA for route optimization.
In the technique disclosed in the following Patent Document 3, when a client or a MN requests an AR whether a sub-network is changed or not, the AR makes a notification of a home prefix only when the sub-network is changed. Thereby, the MN does not generate an address in response to a change of sub-network, thus avoiding interruption of a session.
Further, in the future a mobile node has a possibility of having a plurality of interfaces of different access types such as a WLAN interface, a 3G interface, and a WiMAX interface. Such a different types of plural interfaces can allow a MN to realize advantages of multihoming including load sharing, load balancing, cost down, priority setting to improve QoS, fault tolerance, and reliability. When a MN has a plurality of interfaces, each connecting with a foreign domain, the MN typically registers all care-of addresses with a HA, thus realizing multihoming support.
Non-Patent Document 6 further describes, for example, a method by a MN to register a plurality of care-of addresses (CoA) using a binding identifier (BID) option and a method of allowing a MN to execute bulk registration to a HA concerning binding of a plurality of interfaces using a single BU message.
For instance, in association with a MN 260A with a plurality of different types of interfaces as illustrated in FIG. 11A, location registration signaling has to be conducted plural times. Herein assume that the MN 260A in FIG. 11A is a 3GPP-compatible terminal configuring one or a plurality of home addresses originating from a 3GPP network or a 3GPP operator. Further assume that the MN 260A has two interfaces (interface 1 (IF1) and interface 2 (IF2). The IF1 of the MN 260A connects with a home PMIP domain 250A (MAG 265A), and the IF2 of the MN 260A connects with another foreign PMIP domain 251A (MAG 267A). Assume that these home PMIP domain 250A and foreign PMIP domain 251A further connect with the Internet 252A, and a CN 275A connecting with this Internet 252A has a packet communication session with the MN 260A.
In FIG. 11A, a home agent of MIPv6 for the MN 260A is a LMA/PDN-GW (LMA/PDN-GW/HA) 270A located in the home PMIP domain 250A. In FIG. 11A, the interface 1 of the MN 260A connects with the MAG 265A via wireless link, and the interface 2 of the MN 260A connects with the MAG 267A via a wireless link. Although the following describes based on such a scenario, those skilled in the art can read the description in various scenarios without limiting to this scenario. For instance, as an access technique for a connection between the MN 260A and the MAGs (MAG 265A and MAG 267A), any access techniques such as WLAN, WiMAX, and 3G can be used.
Assume that the MN 260A is supported by some multihoming. When existing in the home domain 250A, the MN 260A may set a common home address for the both interfaces, or may set different home addresses for the both interfaces.
In order to show a major problem in this scenario, assume herein that the MN 260A sets a common home address for the both interfaces of IF1 and IF2, and moves so as to change an access router for the IF1 and IF2 at the same time. The following describes such movement as a simultaneous movement of interfaces. Such a simultaneous movement may occur when the IF2 connects with a WLAN, and the IF1 connects with a small cell such as a WiMAX cell. Assume herein that, in the case of a simultaneous movement, the IF1 of the MN 260A connects with the MAG 265A and other MAGs in the home PMIP domain 250A. As a result of such connections, the MAG 265A (or the other MAGs in the home PMIP domain 250A with which the IF1 of the MN 260A connects) transmits proxy binding update (PBU) 280A to conduct binding between an egress address of the MAG 265A and a home prefix of the MN 260A.
Further, as a result of this simultaneous movement, the MN 260A configures a new care-of address for the IF2 using a unique prefix assigned for each MN by the LMA/PDN-GW 271A. Then, the MN 260A executes BU concerning CMIP through the IF2.
Non-Patent Document 6 further discloses an optimum method of registering a CoA of a MN with a HA by bulk registration conducted by the MN. The bulk registration transmits binding of a plurality of interfaces with one signaling message. Since the MN cannot understand what interface is an ideal one to conduct bulk registration, the bulk registration can be conducted at any interface of the MN. Herein, the ideal interface to conduct the bulk registration is the one enabling the MN to execute quick bulk registration. When one interface of the MN connects with a home domain and another interface connects with a foreign domain, a BU concerning CMIP with a “H” flag added thereto is transmitted from the interface connecting with the foreign domain.
The following Patent Document 4 discloses a method of, when a MN is in a sleep mode or in a not-reachable state, using a proxy server to receive a packet for the MN. According to this method, the MN is not forced to execute transmission of location update signaling to a HA, and can shift to a sleep mode and then acquire data from the proxy server.
The following Patent Document 5 discloses a method of executing fast handoff while coping with a problem concerning handoff such as delay and packet loss. In this case, fast handoff is achieved by transmitting a packet for a MN always to a group of a certain node irrespective of correct binding for the MN and a location of the MN. Before the MN connects with a new access router (AR), the new access router can receive a packet addressed to the MN. In the case where the MN does not connect with the new AR, the packet is abandoned by the AR. Even in the case where the MN connects with another AR, such a packet can be received.
According to the technique disclosed in Patent Document 5, in order to achieve fast handoff basically, a data packet of a MN is multicast to some AR group. That is, according to this method, a packet of a MN is transmitted to one or more base station nodes or access routers no matter whether the MN connects therewith or not. Since it is difficult to expect a precise location of the MN, a packet to be transmitted to the MN is passed to a base station node or proxy group.
The following Patent Document 6 discloses a method where a MN uses a proxy care-of address (proxy-related CoA) related to a foreign agent (FA) as a care-of address of its own. This proxy-related CoA is provided from the FA to the respective MNs. Such an address configuration enables not a MN but a foreign agent to execute encapsulation and decapsulation.
Further, when an AR implements a function of the FA, the method of using the proxy-related CoA as a CoA of the MN can eliminate throughput for encapsulation and decapsulation of tunneling in the MN, thus avoiding tunneling at a wireless link of a large load.    Patent Document 1: US Patent Application Publication No. 20040024901 A1    Patent Document 2: International Patent Application Publication No. WO06/012511    Patent Document 3: International Patent Application Publication No. WO07/050624    Patent Document 4: US Patent Application Publication No. 20040013099 A1    Patent Document 5: International Patent Application Publication No. WO03/090408    Patent Document 6: International Patent Application Publication No. WO02/065731    Non-Patent Document 1: Johnson, D. B., Perkins, C. E., and Arkko, J., “Mobility Support in IPv6”, Internet Engineering Task Force Request For Comments 3775, June 2004.    Non-Patent Document 2: Gundavelli, S., et. al, “Proxy Mobile IPv6”, Internet Engineering Task Force (IETF) Working Group Draft: draft-sgundave-mip6-proxymip6-02.txt, Mar. 5, 2007.    Non-Patent Document 3: Soliman, H., et. al., “Interactions between PMIPv6 and MIPv6: scenarios and related issues” Internet Engineering Task Force (IETF) Working Group Draft: draft-giaretta-netlmm-mip-interactions-00, Apr. 24, 2007.    Non-Patent Document 4: Qin, A., et. al., “PMIPv6 Route Optimization Protocol”, Internet Engineering Task Force Working Group Draft: draft-qin-mipshop-pmipro-00.txt, Feb. 25, 2007.    Non-Patent Document 5: “3GPP System Architecture Evolution: Report on Technical Options and Conclusion”, 3GPP TR 23.882, V1.9.0, Apr. 3, 2007.    Non-Patent Document 6: Wakikawa, R., et. al., “Multiple Care-of Addresses Registration”, Internet Engineering Task Force Working Group Draft: draft-ietf-monami6-multiplecoa-02.txt, Mar. 5, 2007.
Referring now to FIG. 1, the following describes summary of the PMIPv6 protocol or a problem thereof in a 3GPP system. Herein, UE is a term used in 3GPP, while MN is a term used in IETF. In this specification, both mobile hosts (mobile terminals) of the above UE and MN are referred to as MNs (mobile nodes).
FIG. 1 illustrates an evolved 3GPP system configured with various public land mobile networks (PLMN). Access networks illustrated in FIG. 1 are non-trusted WLAN type networks. PLMN typically has a feature in the core networks and the access networks, and 3GPP introduces PMIPv6 also in such a PLMN. When the access networks of PLMN are an evolved 3GPP or legacy 3GPP type access networks, there is a high possibility that the PLMN is managed by a common operator and a router has an address configured with a common route prefix. On the other hand, when the MN tries to access a 3GPP core network via non-trusted WLAN, since a WLAN segment thereof may be managed by a different operator, the access network may directly connect with the Internet.
When a non-trusted 3GPP access or WLAN access is conducted, and in the case where the access network does not connect to the Internet directly or an end receiver of data traffic is located in a 3GPP core network, traffic required going through the 3GPP core network has to be routed through a trusted gateway called ePDG.
In order to describe a problem of the PMIPv6 protocol in a 3GPP system, assume that one operator manages one PLMN in FIG. 1. In FIG. 1, a PLMN 1 has a 3GPP core network 101 and an I-WLAN type access network (described as I-WLAN access network) 103.
The 3GPP core network 101 has a LMA/PDN-GW 50 and a local 3GPP AAA server 60. Assume herein that the LMA functions as a PDN-GW (Packet Data Network Gateway). The local 3GPP AAA server 60 has authorization information on a moving MN to authorize whether the MN can receive a service from the 3GPP core network 101 and a PMIPv6 service (if PLMN introduces PMIPv6).
The I-WLAN access network 103 of the PLMN 1 has an ePDG/MAG 40, an AR 20, and an AR 21. Assume herein that the ePDG has a MAG function. In a scenario of a non-trusted WLAN, the ePDG has to have a MAG function. This is because the ePDG is only one router that the 3GPP core network can trust among routers belonging to the WLAN. Assume further that the PLMN 1 introduces PMIPv6 and the MN 10 connects with this network. In this PLMN 1, the MN 10 connects with the AR 20.
Similarly, a PLMN 2 also has a 3GPP core network 102 and an I-WLAN access network 104, and the 3GPP core network 102 also has a LMA/PDN-GW 51 and a 3GPP AAA server 61. The I-WLAN access network 104 has ePDG/MAG/ARs 30 and 31. Assume herein that the ARs have functions of an ePDG and a MAG. In this PLMN 2, a MN 11 connects with the ePDG/MAG/AR 30. The PLMN 1 and the PLMN 2 (3GPP core networks 101 and 102) connect with a global communication network 100.
In the PLMN1 implementing PMIPv6, a prefix that the MN 10 receives at the time of connection with the I-WLAN access network 103 is an on-link prefix of the AR 20. This results from the AR 20 not implementing a MAG function (it is required to be implemented in a trusted 3GPP gateway ePDG). In this case, the MN 10 cannot understand whether this prefix is suitable for local breakout (packet transmission not going through the home domain of the MN 10 as described later) and route optimization (CoA registration with CN in mobile IP) or not. Even when the MN 10 can understand a property of this prefix (this prefix being an on-link prefix), since a PMIPv6 domain prefix is not acquired, there is a problem that the MN 10 cannot receive a PMIP service in this PLMN 1.
Note here that local breakout means that, when a MN connects with a foreign domain, the MN conducts a communication with a CN without using a route going back to a home domain, and means that when the MN connects with a domain of an operator other than the home domain, the MN conducts a communication (breakout) directly with a CN on the Internet from the foreign domain connecting therewith (if the foreign domain also configures a PMIP domain, via a LMA of the domain), although the communication originally has to go through a LMA (PDN/GW, for example) existing in the home domain to conduct a communication with the CN on the Internet. In this specification, the term of local breakout is further used in a wider sense so that local breakout can express a communication with a CN on the Internet while bypassing the home domain using a globally reachable address (from the Internet) regardless of whether home or foreign domain connecting with the MN and regardless of a type of an access network.
On the other hand, in the PLMN2 implementing PMIPv6, since the AR implements functions of a MAG and an ePDG, a prefix notified from the ePDG/MAG/AR 30 is a PMIPv6 domain prefix. In this case also, the MN 11 cannot understand whether this prefix is suitable for local breakout or not. When the MN 11 uses this prefix (PMIPv6 domain prefix), a communication conducted with a CN connecting with the same PMIPv6 domain (PLMN2) is via a LMA, so that RO cannot be achieved between the MN 11 and the CN.
Referring now to FIG. 2, the following describes a problem occurring when a MN moves in a PLMN implementing PMIPv6. In FIG. 2, assume that a MN 210 connects with a PMIPv6 domain 200 and this PMIPv6 domain is a home domain of the MN 210. Thus, in this case also, a LMA functions as a home agent (HA) of the MN 210. In 3GPP, a SAE (Service Architecture Evolution) anchor can function as a home agent of MIPv6, and also can function as a router implementing a LMA function. That is, in FIG. 2, a LMA/HA/SAE anchor 230 has all functions as a LMA, a HA of the MN 210 and a SAE anchor.
Assume herein that the MN 210 conducts a communication with a CN 211 connecting with the same PMIPv6 domain 200. Assume further that the CN 211 enables RO (RO enabled) and joins to this PMIPv6 domain 200. RO enabled means that the CN 211 can execute RO of CMIP type. The MN 210 further conducts a communication with a CN 213 and a CN 212. Assume that the CN 213 is a RO enabled node existing on the Internet (or public packet data network) 201, and the CN 212 is a node not having a RO function.
Assume further that the MN 210 is a multihoming-enabled node that can configure a plurality of different addresses for one interface. When the MN 210 moves to this PMIPv6 domain 200 to connect with a MAG 220 as an access router and receives both of an on-link prefix and a PMIPv6 domain prefix of the MAG 220, the MN 210 has a possibility of configuring two addresses. For instance, since the MN 210 conducts a communication with a RO-enabled CN such as the CN 211 or the CN 213, the MN 210 may want to use a global prefix (on-link prefix) for route optimization. On the other hand, since the MN 210 exists in the home domain, the MN 210 may want to achieve optimized route in a communication with a legacy CN such as a CN 212 by configuring a home address using a home prefix thereof.
Such an address configuration will make the MN 210 conduct binding update for the home agent (LMA/HA/SAE anchor 230). This BU is of a CMIP type. Similarly, the MAG 20 transmits proxy binding update (PBU) to the LMA (LMA/HA/SAE anchor 230) to associate a home address (PMIPv6 domain address) of the MN 210 with an address of an egress interface of the MAG 220. This BU is of a PMIP type.
FIG. 2 illustrates the BU transmitted from the MN 210 to the LMA/HA/SAE anchor 230 when the MN 210 connects with the MAG 220 with a signal 240. Meanwhile, FIG. 2 illustrates PBU transmitted from the MAG 220 to the LMA/HA/SAE anchor 230 with a signal 241. Similarly when the MN 210 further moves in the PMIPv6 domain (e.g., connecting with a MAG 221 and a MAG 222), double BU signaling (BU signaling of CMIP and PBU signaling of PMIP) will occur. FIG. 2 illustrates such signaling related to movement of the MN 210 with BU signaling (signals 242, 244) and PBU signaling (signals 243, 245). As a result, the movement of the MN 210 (especially when the MN 210 moves fast) causes a series of signaling for a specific purpose (herein signaling related to BU and PBU) very often, resulting in consumption of resource for other communications, thus causing a status called signaling storm (BU storm) generating delay of a data packet and a lack of band.
When the MN 210 understands a global prefix for local breakout, the MN 210 can execute RO with the CN 211 and the CN 213. In this case, a data path subjected to route optimization will be paths 246 and 248. When conducting a communication with the CN 212, the MN 210 uses a PMIPv6 domain prefix. A data packet from the MN 210 to the CN 212 is transmitted to the MAG 220 and is tunneled from the MAG 220 to the LMA 230. The LMA 230 decapsulates a packet, and transmits the decapsulated packet to the CN 212.
As described above, the conventional technique has two types of problems. The first problem resides in that when an AR does not have functions of a MAG and an ePDG, there is a possibility of a MN moving in a PMIPv6 domain failing to understand a PMIPv6 domain prefix and in that when an AR has functions of a MAG and an ePDG, there is a possibility of the MN failing to understand an on-link global prefix. That is, in the conventional techniques, there is a problem that a MN cannot understand various prefixes (a plurality of prefixes) to be selected for efficient communications with various different types of CNs. The second problem resides in that even if a plurality of types of addresses (e.g., an address of a PMIP type and an address of a CMIP type) can be configured from a prefix that a MN can use, BU storm may occur due to double BU signaling (BU signaling and PBU signaling) as described above.
The above-described Patent Document 1 does not mention a problem as to what address is to be selected for local breakout. That is, the MN in Patent Document 1 can understand only an address (global address) used for a communication with a CN or a HA and an address (local address) used for location registration with a MA, and Patent Document 1 does not mention the problem as to what address (or prefix) is to be selected among a plurality of addresses (or prefixes) to achieve efficient communication (route optimization). Patent Document 1 does not mention a problem of route optimization in a local domain also. Since mobility is completely dealt by a MN, the above-described problem generating double signaling (the problem illustrated in FIG. 2) does not occur in the system described in Patent Document 1.
The above-described Patent Document 2 refers to route optimization between a gateway node on the CN side and the LMA. However, Patent Document 2 does not deal with a problem for route optimization under the control of the LMA. The technique disclosed in Patent Document 2 deals with local mobility management by a MN or an AR, and deals with global mobility management by a LMA. This is greatly different from the scenarios illustrated in FIG. 1 and FIG. 2 and a scenario for an operation of the present invention. Patent Document 2 never refers to a problem as to what address is to be used for local breakout. In the technique disclosed in Patent Document 2, an address that the MN understands is a local address only, and route optimization is dealt with by the LMA itself. That is, the technique disclosed in Patent Document 2 does not refer to a problem occurring when the MN selects various prefixes and addresses, and does not cope with the problems illustrated in FIGS. 1 and 2.
In the technique disclosed in the above-described Patent Document 3, since a home prefix only is provided to a MN, the MN does not conduct route optimization. Thus, a communication route is not optimized even with a CN, with which the MN can conduct an efficient communication by route optimization. Further, since only one prefix is provided and the MN does not need to select a prefix among a plurality of prefixes, the technique disclosed in Patent Document 3 does not cope with the problem illustrated in FIG. 1 to select a correct prefix.
According to the technique disclosed in Non-Patent Document 6, as illustrated in FIG. 11A, a length of a path 281A along which BU is transmitted concerning CMIP will be increased. In such a path 281A of a long length to transmit BU concerning CMIP, location updating for IF2 is conducted at a LMA/PDN-GW (LMA/PDN-GW) 271A, and therefore a BU packet of a CMIP type has to be transmitted via a foreign PMIP domain 251A and further via the Internet 252A.
Further, this BU packet has to be subjected to packet encapsulation from the MAG 267A to the LMA/PDN-GW 271A, and this encapsulation processing will further delay location updating.
In this way, according to the technique disclosed in Non-Patent Document 6, there are problems: the care-of address of IF2 is registered through a long length path in the scenario illustrated in FIG. 11A, thus leading to a problem of larger amounts of network resources used (the first problem related to Non-Patent Document 6); and location registration signaling concerning both interfaces of the MN 260A is conducted as indicated with the paths 280A and 281A of FIG. 11A, thus leading to the necessity of optimization to decrease signaling load in the network (the second problem related to Non-Patent Document 6). In the scenario disclosed in FIG. 11A, the MN 260A conducts updating (path 281A), whereas a fixed entity (MAG 265A) conducts another updating (path 280A) concerning location information.
As for a method using bulk registration disclosed in Non-Patent Document 6, a MN does not control all signaling, and there is a problem that the MN cannot transmit signaling of bulk registration in the scenario illustrated in FIG. 11A (the third problem related to Non-Patent Document 6). That is, in FIG. 11A, the MN 260A conducts location updating signaling of some interface, whereas the MAG 265A conducts location updating signaling of another interface. Even if the MN conducts signaling of bulk registration through IF2, it takes a long time for the bulk registration of interfaces to reach the LMA/PDN-GW 270A, so that the above-stated problem cannot be solved.
According to the technique disclosed in Patent Document 4, signaling to a HA will be decreased. However, a MN has to acquire data from a proxy server via a plurality of interfaces, so that the MN has to conduct some binding registration to the proxy server. There may be a method of allowing the MN to execute quick and optimized location registration with the proxy server for one or a plurality of interfaces. However, this provides a solution different from the technique of the present invention, and this specification does not describe it.
The following describes a scenario causing a handoff problem when a multi-interface MN moves in a home PMIP domain and a foreign PMIP domain. In FIG. 11B, assume that a MN 260B has two interfaces (IF1 and IF2) and the MN 260B connects with a home PMIP domain 250B through both of the interfaces in the initial state. Assume further that the MN 2608 acquires one or a plurality of home prefixes from a LMA/PDN-GW (LMA/PDN-GW/HA) 270B. In the initial state, IF2 of the MN 260B connects with a MAG 266B, and IF1 of the MN 260E connects with another MAG (not illustrated in FIG. 11B) in the home PMIP domain 2508.
When IF2 of the MN connects with the MAG 266B via an access link, the MAG 266B transmits PBU 280B to conduct binding between the home prefix and an egress address (address of an egress interface) of the MAG 266B. This registration with the PBU 280B creates an entry at the LMA/PDN-GW 270B. The entry of binding cache by this registration is illustrated in a first entry in binding cache 271D of FIG. 11D.
Assume that immediately after moving to connect with the MAG 265B via an access link, IF1 moves away from the home PMIP domain 250B and connects with a foreign domain (access domain) 251B via an access link. Assume further that the home PMIP domain 250B and the foreign domain 251B connect with the Internet 252B. Herein, the home PMIP domain 250B can be configured with a plurality of different types of access networks. The foreign domain 251B may be or may not be configured with architecture based on PMIP.
When IF1 of the MN 260B moves to connect with an AR 267B, the MN 260B configures a care-of address for IF1 and thereafter executes BU (via a path 282B) of CMIP with respect to the LMA/PDN-GW 270B. This BU via the path 282B may reach the LMA/PDN-GW 2708 earlier than PBU 281B from the above-stated MAG 265B.
In such a case, an entry in the binding cache 271D for IF1 as illustrated with a second entry in the binding cache 271D of FIG. 11D is created at the LMA/PDN-GW 270B.
Herein, an interface is identified with an interface identifier, and as illustrated in FIG. 11D, the binding cache 271D includes a parameter of the interface identifier (IF-ID/BID). Binding cache keeps an entry for PBU of PMIP or BU of CMIP concerning any and each interface.
When the PBU 281B reaches the LMA/PDN-GW 270B from the MAG 265B later than the BU of CMIP via the path 282B, this PBU 281B overwrites a correct BU entry of CMIP (the second entry in the binding cache 271D of FIG. 11D), resulting in a third entry created in the binding cache 271D of FIG. 11D.
When such entry registration of wrong reaching order occurs, and in the case where the LMA/PDN-GW 270B assigns a common prefix to both of the interfaces of the MN 260B, packet reachablity via IF1 cannot be achieved until correct binding arrives from IF1 of the MN 260B. In such a case of assigning a common prefix, no packet is transmitted via IF1, and only packet transmission via IF2 is possible.
On the other hand, when the LMA/PDN-GW 270B gives a unique prefix to each interface of the MN, the MN 260B may configure a different and unique home address using each prefix. When a wrong binding cache entry for IF1 occurs in the case of assigning a plurality of prefixes, a data packet to be delivered to a home address configured in IF1 will not reach the MN 260B until correct binding for IF1 is established at the LMA/PDN-GW 270B.
Basically, until another correct BU of CMIP reaches the LMA/PDN-GW 270B, packet loss due to handoff for IF1 and handoff delay will occur. Such packet loss and handoff delay will degrade QoS quality of a flow sensitive to delay and data flow of important information.
The technique disclosed in Patent Document 5 may solve the above-stated problem illustrated in FIG. 11B. However, this technique multicasts a data packet, and therefore large amounts of network resources are required, thus wasting network resources.
In order to access a 3GPP core network in a non-trusted WLAN access, a packet has to be transmitted via a trusted gateway called ePDG. However, since the ePDG is a router existing in a WLAN access domain located higher in rank in a routing hierarchy, the ePDG is not always a direct access router for a MN in such a network configuration. In such a network configuration of the ePDG, when a MN receives prefixes of different types, the MN can select an appropriate prefix to configure a CoA for route optimization with a CN, depending on a location of the CN and a location on the network.
In FIG. 11C, a MN 205C connects with a home PMIP domain 202C via a non-trusted WLAN access network (non-trusted WLAN) 203C and conducts communications with two CNs (CN 210C and CN 211C). The CN 210C connects with an AR 217C located in the WLAN access network 2030. On the other hand, the CN 211C connects directly with a MAG 221C, and is located in a trusted WLAN access network (trusted WLAN) 200C. The home PMIP domain 202C connects directly with the Internet 201C.
Assume that in the initial state the MN 2050 connects with an AR 2150 and moves as in a trace 206 of FIG. 11C. When the MN 205C decides to use a home address to communicate with some CN (not illustrated), then the MN 205C firstly tunnels a data packet to an ePDG/MAG 220C. This data packet is decapsulated by the ePDG/MAG 2200, and is further tunneled to a LMA/PDN-GW (LMA/PDN-GW/HA) 230C as a HA of the MN 2050.
In this PMIP core network (home PMIP domain 2020), a GW 231C further exists, and assume that this GW 231C is located lower in rank in the routing hierarchy than the LMA/PDN-GW 230C. Basically, this GW 2310 can conduct some policy and execute an AAA service (e.g., accounting management) with respect to a MN accessing the 3GPP core network. Assume further that the GW 231C connects with the Internet 201C. A packet from the MN 205C can be tunneled via the GW 231C in accordance with policy set at the GW 231C.
In such a scenario, the MN 2050 may receive two types of prefixes. For instance, one of the two types of prefixes may be a logically correct on-link prefix provided from the AR 2150, and the other type may be a home prefix of PMIP transmitted from the ePDG/MAG 220C when the MN 2050 establishes tunnel with the ePDG/MAG 220C. Signaling 240C of FIG. 11C illustrates two prefixes received from the AR 215C. These two prefixes are received at the MN 205C at different timings.
If the CNs configure their care-of addresses using a prefix of the PMIP domain, the MN 205C can understand that these two CNs are located in the same PMIP domain as the MN 205C to conduct route optimization signaling (e.g., signaling according to a RR test) with the CN 2100 and the CN 211C. In such a case, the MN 205C may use an on-link prefix generated by the AR 215C to establish a route optimization session with the above-stated CN 210C and CN 2110.
A problem occurring when such an on-link prefix is used resides in that, in the case where the access domain (WLAN access network) 203C is quite wide and a large number of ARs exist therein, the MN 205C may have to configure a different care-of address every time the MN 205C connects with a different AR in the WLAN access network 203C, and starts a route optimization session with a CN. Further, when the MN 2050 configures a care-of address at each AR location in the access network 203C, the MN 205C has to transmit binding to associate such a care-of address with a HoA to the HA 230C for updating, whereby signaling load in the PMIP core network (home PMIP domain 2020) will increase.
Further, these location registration signaling packets are tunneled to the ePDG/MAG 220C and decapsulated, and then sent out to the LMA/PDN-GW (LMA/PDN-GW/HA) 230C. When the MN 2050 connects with the AR 215C, the location registration signaling is transmitted as illustrated in paths 241C and 243C. On the other hand, when the MN 205C connects with the AR 216C, the location registration signaling is transmitted as illustrated in paths 242C and 244C.
When the ePDG/MAG 220C provides the MN 205C with a home prefix, the ePDG/MAG 220C can update binding concerning PMIP in the LMA/PDN-GW/HA 230C. Note here FIG. 11C does not illustrate this case. A problem in this case is that since a large number of ARs exist in the access domain (WLAN access network) 203C, an on-link prefix may not be in an ideal state and another prefix may have to be searched.
According to the technique disclosed in Patent Document 6, although load on tunneling from a MN to an AR via a wireless path can be decreased, the problem illustrated in FIG. 11C cannot be solved.